RS232 on a network

I have 3 ti545 PLC's which I can program individually via their respective RS232 ports. I would like to use one PC and connect to the 3 of them so I can program them all from the one place. Do i need some sort of RS232 hub to get the multiple connections?

Three main options.

There are Ethernet to 4 serial port adapters and USB to 4 serial port adapters.

I would use a simple one to four mechanical switch.

The adapters tend to slow communications a bit and are more expensive.

I favor installing Ethernet cards in each of the processor racks...but I am not absolutely certain you can program over the ethernet. Maybe someone else does. Anyway, assuming you can, I would then tie them all into a central hub and to the PC.

As a word of caution, I feel strongly that one should NEVER program a plant floor PLC remotely.

The reason for this is simple: Things can go wrong.

If you are right there at the PLC itself, you are more apt to know when something unexpected occurs.

Safety is of utmost importance.

Steve

You can program the Ti545 over ethernet, but you can not use TiSoft. You need to use Workshop by FasTrak software which is the Windows based software for the TI505 series of processors. The ethernet module for the TI545 is the CTI-2572 module and is made by CTI not by Siemens. The list price for the module is about $1700.00 ea. So networking 3 processors is not a cheap option. The systems I use it on already have the ethernet module installed to handle communications to a Windows based PC. I can make a dial up connection to the PC and then access the PLC over this RAS connection. It is much easier then hanging a modem on the serial port and it allows me to access all of the processors over one modem connection without having a manual switch to choose between processors. It makes remote support much easier. Also some of our clients give use VPN connections into their plant network so I can have network speed remotely instead of the limits of a modem.

Steve Etter said:

As a word of caution, I feel strongly that one should NEVER program a plant floor PLC remotely.

Click to expand...

I dislike the words "never" and "always." You've (ALWAYS ) got to leave room to grow.

If we NEVER cut down trees, then forest fires can wipe out half a state.

If we ALWAYS shread documents, then we look like idiots when the Feds come knocking on the door.

Likewise, a little remote online edit can save you a pricey plane ticket. Who wants to go to Darkhole, Alaska to find out that somebody's just been screwing with setpoints?

AK

I will accept that free offer for a lovely vacation in Alaska!!!

Controling servo motors, another exception

We have two servo motors that are on-line over the internet almost all the time. We use them to do demonstrations. Yes, we allow the customers to control our motor over the internet. Yes they are small and safe.

There is nothing quite like a hands-on on-line demomonstration to prove the we can do the job and the the customer feel confident that he can do the job.

We also do on-line tech support. The customer can show me what he is doing. They I can see why it doesn't work the way the customer intended.

I have also done applications in steel mills that are so large that one is two hundred yards away from the equipment that is being controled and definitely out of sight. You have spotters for safety in this case.

Thanks for the input guys, I will advise my client of the costs and see which way he wants to go. You responses have been much appreciated

I believe the CTI 2572 also offers a serial redirect feature that will allow you to communicate serially to multiple PLC's using the module on an Ethernet network. If I understand it correctly, this would allow you to use TISOFT with the serial connection to do what you request. TISOFT (as does Softshop/Workshop) also supports H1 Ethernet if you chose to go that route. For the CTI modules, go to

http://www.controltechnology.com/products/505/505mods-com.htm

There is a DOS Based Network called TI-WAY, as in Texas Instrument-WAY.

You can have multiple PLC's and multiple PC's.

You need a TI-Way card for the PC's and a NIM (Network Interface Module) for each PLC.

You can program any PLC (On-Line) from any PC using TiSoft.

I agree with Terry that TIWAY is a viable solution. However, if I remember correctly, the TIWAY NIM does not support the task codes that allow FORCE, UNFORCE, and FIND (except FIND address). So, whether or not those functions are needed should probably be considered before selecting TIWAY. Take this with a grain of salt, though. My memory is fading as fast as my hairline.

I agree with Terry that TIWAY is a viable solution. However, if I remember correctly, the TIWAY NIM does not support the task codes that allow FORCE, UNFORCE, and FIND (except FIND address). So, whether or not those functions are needed should probably be considered before selecting TIWAY. Take this with a grain of salt, though. My memory is fading as fast as my hairline.

The FORCE and UNFORCE do work. Only the FIND ELEMENT doesn't work On-Line. It works fine OFF-Line.

I just wrote about this in another thread... Search Me! (or maybe Find Me?)

Terry,

Thanks for the update. I had looked at the electronic version of a manual for TISOFT 6.3 and the section on using TISOFT with TIWAY indicates that FORCE/UNFORCE were not allowed in RUN mode. However, the last version of TISOFT I got was 7.1. It probably pays to read the release notes. We usually use the Unilink Host Adapter instead of the host adapter card, but I bet it will work the same way. I'll give it a try. It will come in handy. It is always nice to know of another tool in the toolbox.

Thanks again.